Optimized high-performance concrete using Styrene–Butadiene Rubber and hybrid fibers: enhancing fresh, mechanical, durability, and microstructural properties for sustainable construction

Abstract

Building on our previous research, which identified 3% Styrene–Butadiene Rubber (SBR) and 10% silica fume replacement by cement as optimal for High-Performance Concrete (HPC), this study investigates the combined effects of SBR and hybrid fibers (50% glass fibers and 50% polypropylene fibers) at varying proportions (0.25–2%) on the fresh, mechanical, durability, and microstructural properties of HPC. The mix design adhered to IS 10262:2009, with testing conducted as per IS 516:1959 standards. Results indicate that adding SBR improves workability, while hybrid fibers enhance tensile and flexural strength through crack-bridging mechanisms. The optimal composition, with 3% SBR and 1% hybrid fibers, achieved a 20% increase in compressive strength compared to the control. Durability studies demonstrated reduced permeability, improved freeze–thaw resistance, and better chemical attack resistance. Microstructural analysis via SEM, TGA, and XRD revealed a dense interfacial transition zone (ITZ), reduced porosity, and higher C–S–H content, contributing to superior mechanical and durability properties. This comprehensive study establishes the benefits of SBR and hybrid fibers in producing sustainable and high-performing concrete, aligning with IS code recommendations. The findings provide a robust framework for enhancing concrete performance in diverse construction applications.